I've recently set up my server so that my suPHP 'virtual' users can't be logged into by using this article

My issue now is that before when I ran a rake command for my Ruby on Rails application running on the server, I used su to go into www-data and execute the command from there - obviously I can't do that anymore because of the nologin.

So as a root user, how can I execute commands as other user's, even if they are nologin?